Consider the charge configuration and spherical Gaussian surface as shown in the figure.When calculating the flux of the electric field over the spherical surface, the electric field will be due to.

 

The inward and outward electric flux from a closed surface are respectively $8\times {10}^3$ and $4\times {10}^3$ units. Then the net charge inside the closed surface is

A disc of radius $\frac{a}{4}$ having a uniformly distributed charge $6\mathrm{C}$ is placed in the $x-y$ plane with its centre at $\left(-\frac{a}{2},0,0\right)$ Fig. 3.78. A rod of length $a$ carrying a uniformly distributed

charge $8C$ is placed on the $X-$axis from $x=\frac{a}{4}$ to $x=\frac{5a}{4}$. Two point charges $-7C$ and $3C$ are placed at $\left(\frac{a}{4},-\frac{a}{4},0\right)$ and $\left(-\frac{3a}{4},\frac{3a}{4},0\right)$ respectively. Consider a cubical surface formed by the six surfaces $x=\pm \frac{a}{2},y=\pm \frac{a}{2},z=\pm \frac{a}{2}$. The electric flux through the cubical surface is

A uniformly charged thin spherical shell of radius $R$ carries uniform surface charge density of $\sigma$ per unit area. It is made of two hemispherical shells, held together by pressing them with a force $F$ (see figure), $F$ is proportional to